CO2 uptake in calcium aluminosilicate materials

CO₂ mineralization has gained increasing attention as a strategy to reduce emissions from concrete production. This study investigates the carbonation potential of several calcium aluminosilicate (CAS) materials, model systems for understanding supplementary cementitious materials (SCMs). CAS materials were synthesized at temperatures ranging from 1000 °C to 1600 °C, producing structures ranging from partially crystalline to fully amorphous. X-ray diffraction and scanning electron microscopy were used to understand material physicochemical properties. Carbonation potential was assessed through CO₂ uptake measurements using thermogravimetric analysis and Fourier-transform infrared spectroscopy, while SCM reactivity was evaluated via a modified R³ test. Results show that materials synthesized at 1000 °C and 1200 °C, containing unreacted oxides, portlandite, CA, and C₂S, exhibited the highest CO₂ uptake but the lowest reactivity as SCM. In contrast, fully amorphous glasses synthesized at 1600 °C demonstrated significantly higher SCM reactivity but minimal CO₂ uptake. These findings highlight a fundamental trade-off between their reactivity and carbonation potential, governed by the degree of amorphization.